REX, is a five star hotel, composed of 159 individually designed guestrooms, a range of function and meeting rooms and four in-house restaurants, café and bar in Ho Chi Minh City. The hotel was awarded the 2008 ASEAN Energy Award and the incentive prize for the Refurbishment Building in the 2012 Energy Efficiency Building Contest. Many energy saving solutions have been applied such as using a solar heat water system, installing heatpumps and designing and installing a vertical garden.

Third Party Verified: No
Source of Information: Rex Hotel
Methods of data collection: interviews with manager and data collection via email.

The building is orientated northwest and takes advantage of prevailing winds from the southeast.Building Envelope

Windows
The window to wall ration (WWR) is 40%. According to the Energy Efficient Building Code – Building Envelope Guideline (EEBC), WWR must be between 30-50% (EEBC 2013).
All windows and balcony doors are double glazed. It provides an insulation capacity that helps to reduce the thermal load for AC systems.WallsColor
White and light – yellow painted walls allows a high solar reflection capacity. It helps to reduce the thermal inertia of the building.Shading
• The large balcony on the first floor is covered with grass, it aims to reduce solar radiation to the wall and glass sections to facade and main entrance below.
• The building has a vertical garden that is the largest in Viet Nam with over 600m2 of green area comprised of 30 species of plants. It helps to reduce the ambient temperature, creates extra shading as well as a beautiful enviroment.

Roof – TerraceShading
Solar water heating panels are used to collect solar energy but also helps to reduce solar radiation on to the roof surface.
The terrace is shaded by a lot of trees that reduce solar radiation.
Over Thermal Transfer Value (OTTV) of the roof is calculated by ECC Ho Chi Minh at 21.01 W/m2, a reduction of 65% compared to the EEBC requirement (of 60W/m2).

Façade materials
Installation of an insulation layer with low thermal inertia materials such as timber flooring to reduce heat transfer through the terrace.

HVAC

1. Centralised air conditioning
Installation of a Variable Refrigerant Volume system with COP = 3.28, a 10.8% improvement compared to the EEBC requirement (of 2.96).

2. An air conditioning control system
Installation of an air conditioning control system to control temperature, time and operation of all AC system such as AHUs, fans and pumps.

Lighting

1. Installation of energy efficient lamps
(11 W and 18 W) Compact fluorescent light lamps are installed in lobbies, guest rooms and public areas.
Lighting Power Density (LPD) for terrace: is 3.5 W/m2, a reduction of 68% compared to the EEBC requirement.

2. Control of lighting
Occupation sensors have been installed in toilets to avoid unnecessary energy consumption.

Building Loads

1. Hot water system• Installation of a solar water heater with a capacity of 1,800 liters/hour. It provides 80% of the hot water, saving 40 MWh/month.• Replacement of (90 kW total) two electric boilers with (25 hp total) five heat pumps that not only reheat warm water from the solar hot water system in bad weather but also provides (26-27 C) cool air to laundry areas.

Maintenance
1. Implementation of a preventative maintenance , repair and replacement plan for each family of equipemnt.
2. Qualified Technical Staff (34 members)in several fields such as eletricity, electronics, plumbing,…
They perform 97,920 hours of maintenance works per year to ensure continuous operation for the hotel and provides a high level of customer service.